The present invention relates to a solenoid valve with a tubular metallic core and in particular to such a solenoid valve comprising an electromagnetic coil wound on the hub of a bobbin of a plastic material, a central metallic core disposed in the hub of the bobbin, the said core forming an axial conduit, and an armature which can be displaced by electromagnetic forces axially towards an end of the said axial conduit in order to control the flow of gas in the said conduit.
Such solenoid valves are in particular used in feed systems for the combustible mixture of internal combustion engines.
In these devices the coil is supplied with intermittent current of a cyclic ratio which can vary from 0 to 100%, so as to vary the distance between the armature, generally supporting a sealing joint, and the end of the central tubular core. The effect of this is to determine the output of the valve for a given value of differential pressure prevailing at both sides of the valve.
It is consequently understood that a critical problem with this type of solenoid valve resides in the adjustment of the distance, at rest, between the armature and the end of the axial conduit. This distance was previously determined by virtue of extremely precise machining and assembly of the different pieces of the solenoid valve. This led to high costs.
The present invention aims to overcome this difficulty by providing a solenoid valve of-the aforementioned type which does not require particularly precise machining and which is quick and easy to adjust.